thumb index
noun
1.
a series of labeled notches cut along the fore edge of a book, to indicate the divisions or sections.
Origin
1900-05
thumb-index
[
thuhm
-in-deks]
/ˈθʌmˌɪn dɛks/
verb (used with object)
1.
to provide (a book) with a thumb index.
British Dictionary definitions for
thumb index
thumb index
noun
1.
a series of indentations cut into the fore edge of a book to facilitate quick reference
verb
2.
(
transitive
) to furnish with a thumb index